This application relates generally to a fluid control valve and more particularly to a temperature responsive valve for use with a transmission oil reservoir.
Hydraulic pressure systems as used in motor vehicles require a supply of transmission fluid and the maintaining of a constant oil level in the transmission oil pan at all operating temperatures for trouble free transmission performance. Conventionally the oil pan serves as a sump to provide the necessary supply, however, in front wheel drive vehicles the transmission oil pan is too shallow to hold a suitable quantity. The problem is exacerbated by the fact that the volume of the oil used expands in the order of thirty eight percent at elevated temperatures. The problem has been dealt with by employing an auxiliary reservoir, for example, in the side of the transmission case cover. The fluid level in the auxiliary reservoir is controlled by a thermostatic element which controls the opening and closing of a cover plate in the transmission housing in response to the temperature of the oil in the auxiliary reservoir. As the temperature of the oil in the reservoir decreases the cover plate opens allowing the oil to drain into the lower sump or oil pan to maintain the desired oil level.
Examples of such valves are as set forth in U.S. Pat. Nos. 4,865,250 and 4,921,165 issued on Sep. 12, 1989 and May 1, 1990 respectively assigned to the assignor of the instant application.
Although these valves have proven to generally provide the desired function there still has been inconsistent operation flow control from one transmission to another which it is desirable to correct. Such inconsistency can lead to faulty operation of a certain number of the transmissions in which the valves are incorporated.